I'm very happy about how well the game is received!
Short answer:
No sorry. Play With Gilbert wasn't created with co-op in mind and I couldn't implement it without basically recreating all the game mechanics.
Long Answer:
One of the main reasons I started on Gilbert's World is that Play With Gilbert was not created with co-op from the outset. It was just meant for my then 4 year old daughter to play but I realized afterwards she might want to play with me. I had no experience with co-op mechanics and therefore I tacked it on.
Gilbert's world is completely co-op friendly. Right now the game can be played up to four players and each player can customize their kitty. Customization is currently tied to player 1 to 4 but I am looking into ways to make these preset profiles instead.
Anyway, the game is in a highly playable state and I would very much like to ask if you would want to participate in me receiving some feedback while I'm still developing. Currently I am merely just eager to learn how the youngster react to the new game and if it is indeed an improvement to Play With Gilbert and making sure the game runs as well or better than Play With Gilbert.
If you want I can invite you to my Discord server and help set you up. The only thing that really needs a lot of work is the UI/menu systems. They are very functional but not practical which is something I will be sinking time into very soon.
Anyway, as I said there's much more customization options and more minigames and things to do. Just only one (Pretty big) level (Island) which will be added to in the near future. Let me know and I'll share an invitation. :)